“We are trying to coat chrome alloy steel tubing with transparent blue powder and a white powder. The steel tubing is stamped with its specs with a yellow dye. When we coat this product and after a little curing time the yellow dye bleeds through.
We have tried to solvent wash and sand the yellow off. Even though it appears that we get the yellow off it still bleeds back through our coating. What can you suggest? “
“The problem is “transparent” powders will not hide any defects on the substrate. Therefore, complete removal of this yellow ink is required. Solvent wiping will just dilute the ink an spread it around the surface. An aqueous cleaner with high impingement (mechanical action) can produce the best results. A light sanding with a fine grit paper should follow the cleaning. Contact a pretreatment chemical supplier for an aqueous cleaner (alkaline or acidic).”